/
plugin_cache.go
164 lines (134 loc) · 3.35 KB
/
plugin_cache.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
package main
import (
"crypto/sha512"
"encoding/binary"
"sync"
"time"
"github.com/miekg/dns"
sieve "github.com/opencoff/go-sieve"
)
const StaleResponseTTL = 30 * time.Second
type CachedResponse struct {
expiration time.Time
msg dns.Msg
}
type CachedResponses struct {
sync.RWMutex
cache *sieve.Sieve[[32]byte, CachedResponse]
}
var cachedResponses CachedResponses
func computeCacheKey(pluginsState *PluginsState, msg *dns.Msg) [32]byte {
question := msg.Question[0]
h := sha512.New512_256()
var tmp [5]byte
binary.LittleEndian.PutUint16(tmp[0:2], question.Qtype)
binary.LittleEndian.PutUint16(tmp[2:4], question.Qclass)
if pluginsState.dnssec {
tmp[4] = 1
}
h.Write(tmp[:])
normalizedRawQName := []byte(question.Name)
NormalizeRawQName(&normalizedRawQName)
h.Write(normalizedRawQName)
var sum [32]byte
h.Sum(sum[:0])
return sum
}
// ---
type PluginCache struct{}
func (plugin *PluginCache) Name() string {
return "cache"
}
func (plugin *PluginCache) Description() string {
return "DNS cache (reader)."
}
func (plugin *PluginCache) Init(proxy *Proxy) error {
return nil
}
func (plugin *PluginCache) Drop() error {
return nil
}
func (plugin *PluginCache) Reload() error {
return nil
}
func (plugin *PluginCache) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
cacheKey := computeCacheKey(pluginsState, msg)
cachedResponses.RLock()
if cachedResponses.cache == nil {
cachedResponses.RUnlock()
return nil
}
cached, ok := cachedResponses.cache.Get(cacheKey)
if !ok {
cachedResponses.RUnlock()
return nil
}
expiration := cached.expiration
synth := cached.msg.Copy()
cachedResponses.RUnlock()
synth.Id = msg.Id
synth.Response = true
synth.Compress = true
synth.Question = msg.Question
if time.Now().After(expiration) {
expiration2 := time.Now().Add(StaleResponseTTL)
updateTTL(synth, expiration2)
pluginsState.sessionData["stale"] = synth
return nil
}
updateTTL(synth, expiration)
pluginsState.synthResponse = synth
pluginsState.action = PluginsActionSynth
pluginsState.cacheHit = true
return nil
}
// ---
type PluginCacheResponse struct{}
func (plugin *PluginCacheResponse) Name() string {
return "cache_response"
}
func (plugin *PluginCacheResponse) Description() string {
return "DNS cache (writer)."
}
func (plugin *PluginCacheResponse) Init(proxy *Proxy) error {
return nil
}
func (plugin *PluginCacheResponse) Drop() error {
return nil
}
func (plugin *PluginCacheResponse) Reload() error {
return nil
}
func (plugin *PluginCacheResponse) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
if msg.Rcode != dns.RcodeSuccess && msg.Rcode != dns.RcodeNameError && msg.Rcode != dns.RcodeNotAuth {
return nil
}
if msg.Truncated {
return nil
}
cacheKey := computeCacheKey(pluginsState, msg)
ttl := getMinTTL(
msg,
pluginsState.cacheMinTTL,
pluginsState.cacheMaxTTL,
pluginsState.cacheNegMinTTL,
pluginsState.cacheNegMaxTTL,
)
cachedResponse := CachedResponse{
expiration: time.Now().Add(ttl),
msg: *msg,
}
cachedResponses.Lock()
if cachedResponses.cache == nil {
var err error
cachedResponses.cache = sieve.New[[32]byte, CachedResponse](pluginsState.cacheSize)
if cachedResponses.cache == nil {
cachedResponses.Unlock()
return err
}
}
cachedResponses.cache.Add(cacheKey, cachedResponse)
cachedResponses.Unlock()
updateTTL(msg, cachedResponse.expiration)
return nil
}